“Droid” ceramic loudspeaker enclosure. Technical input; Bowers & Wilkins, Wedgwood and Staffs. MA ceramics department. © Richard Grant 1996.
The development of the above design is a fascinating journey; my post-graduate involved 3D computer modelling and rapid prototyping utilising stereo lithographic resin system (1996). At that time the software was bespoke for creating organic shapes suitable for slip casting and other ceramics manufacturing methods and had to be run on Silicon Graphics Indy computers. The course was sponsored by the E.U and all the big guns in the Stoke area ceramics industries at that time. This rather usefully gave me a free hand in putting a pet project of mine to the head honchos at Wedgwood. I presented the following quick concept sketches, scamps and images for my “Droid”:
I outlined to the Wedgwood design manager how a ceramic body is ideal for a loudspeaker enclosure due to its rigidity resulting in virtually nil low frequency (LF) colouration, and that any other extraneous acoustic leak through the ceramic body could be mitigated quite simply; further that the mid Blue Jasper Ware body colour would perfectly compliment the Kevlar yellow drive units I had in mind… He gave me a blank stare and said: “Follow me”. I did; he literally took me next door (the next line manager’s office along) and said “repeat what you just said to me…” The second chap, once I had finished said “hmmm, follow me”. I did. We went next door to the third office and I was duly asked to repeat my performance again.
Again, once I had finished: “hmmm, follow me” !
If I remember correctly it was at the fourth point I was taken to the final link in the chain and had convinced the right four managers and line controllers for the factory, design, staff and technical that it would fly. I got the Green light!
Enter Bowers & Wilkins; In the second and final years of my product degree I had been in touch with the Steyning based research and applied physics department of Bowers & Wilkins (B&W) loudspeakers. One of their top applied physicists’ had been very helpful and I approached him again. I requested and he kindly supplied a set of drive units and technical info relating to vent and volume required for them to perform optimally.
All I had to do know was make my first ever plaster pattern for a large slip casting mould to be used by the most notoriously difficult casting clay body, Jasper ware. Being near its vitreous point when fired Jasper Ware not only shrinks by a large percentage but is prone to distortion.
No pressure then.
I created a simple maquette based on my sketches (below left) and started to make the large and rather cumbersome pattern required. Staffordshire MA workshops also happened to be part of the access deal with the Hothouse course so in I went:
Following the pattern element creation a clay wall system was made to allow the pouring of the first half of the slip casting mould. Once the first half had set I then had to correlate the plug for the LF reflex and an insert plug to give proper return on the main drive unit pour hole (both inserts shown below left, second half pour casing shroud to right):
Now with a large heavy mould and after long hours in the drying cupboard in the MA workshop I trundled off to Burslem and the Wedgwood production lines. Literally into the history books (below left). I was afforded a Jasper Ware technician to produce my castings, he also kindly fettled my mould and added pouring accoutrements and necessities such as a clay collar etc (below right):
Once the Jasper slip was poured, left to soak briefly and emptied something resembling a hollow enclosure of my design could emerge:
The soft shell is left to harden supported by the mould half and eventually becomes leather hard. this is the perfect time to fettle, de-bur, cut and add holes to the body prior to firing:
Once in fine fettle the Jasper Ware contrast sprig is added, in this case a relief ellipse with my signature, B&W/Blue Room and the historic Wedgwood name:
There was a lot to do to prep the castings for firing; As Jasper Ware distorts readily in firing it needs supporting and caressing through the heat process. A conical ring is placed into the large pour opening to help keep integrity (below left) and the body is nestled into a special sand bed to give spread support (below right):
Once fired and cooled the amount of shrinkage immediately becomes apparent:
We put on a small exhibition of the projects completed at the Hothouse centre, Longton – Staffordshire (below, “Droid” enclosure prototype in Jasper Ware):
I have developed the design and its manufacturing with batch produced versions in differing glazes, paint finishes and experimental finishes (below, “Droid” design in an Earthenware body with Sky Blue/Lime Green test glaze):
I continued to be involved with Bowers & Wilkins discussing and drawing up ceramic enclosure inserts for use on prototype B&W 801 models. This involved the tear shaped Mid range enclosure mounted a top the LF enclosure, as a ceramic option. The principle of a very dense enclosure for this crucial drive unit has gone on to be a huge success using injection moulded high density loaded plastics (below left, B&W 801 speakers showing mid range enclosure featuring yellow Kevlar cones in drive units) (below Right, B&W 801 Mid range enclosure detail):
Following this early episode in my professional career I kept in touch with the B&W senior Applied Physicist and he has gone on to produce some notable work at Vivid Speakers. Bear in mind he was also responsible for the Nautilus whilst at Bowers and Wilkins. My “Droid” design for a high concept product enclosure was toyed with by Blue Room (then a subsidiary of the much larger B&W) as a potential follow up to their successful “Mini Pod” Speaker, however royalty negotiations did not conclude successfully.
(Below Left, Nautilus speaker B&W) (Below Right, Mini POD Blue Room/Scan):
I have pushed on with my ceramic enclosure projects, specialist enclosures and subsequent manufacturing materials testing and it remains the core of my product development research work. This and other aspects of my work are extensively covered in my website so please feel free to dig deeper. © Richard Grant 1996-2011